Answer : Option C , ALO2
1. calculate number of moles for Aluminimun ;
given that mass = 3.91 g
Molecular mass =26,98
∴ moles = 3.91 g/26.98
= 0.144 moles
2. Calculate number of moles for Oxygen
given that mass = 3.49 g
Molecular mass =16g/mol
∴ moles = 3.49g/16g/mol
=0.218 moles
3. Divide all components by the smallest value:
• Aluminium : 0.144 /0.144 moles= ,1 mole
,
• Oxygen : 0.218 /0.144 =1.5 moles≈ ,2 moles
Therefore the emperical formula is AlO2